Process of extracting precious metals from ores.



. L. B. DARLING. PROCESS OF EXTRAGTING PRECIOUS METALS FROM URES.

Patented Aug. 5, I902.

(Application filed Feb. 12, 1902.)

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' No. 706,303. j Patnted Aug. 5 I902.

L. B. mmmm PROCESS OF EXTBAGTING PRECIOUS METALS FROM (IRES.

(Application filed Febh 12, 1902) (N0 Muriel.)

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TATES" PATENT OFFICE.

LEVI B. DARLING, OF PROVIDENCE, RHODE ISLAND.

PROCESS OF EXTRACTING PRECIOUS METALS FROM ORES.

SPECIFICATION forming part of Letters Patent'No. 706,303, dated August5, 1902. Application filed February 12, 1902. Serial No. 93,705. (Nospecimens.)

To all whom, it may concern.-

Be itknown that I, LEVI B. DARLING, a cilizen of the United States ofAmerica, and a resident of Providence, in the county of Providence andState of Rhode Island, have invented certain new and useful Improvementsin Methods or Processes of Extracting Precious Metals from Ores, ofwhich the following is a specification.

My invention relates to improvements in methods or processes for theextraction of gold and other precious metals from finelydivided ores;and it consists, essentially, in spreading a comparatively thin layer ofslimepulp containing the metal over a substantially fiat surfaceprovided with strainer-covered channels communicating with the sump,then covering the pulps surface with a thin layer of themetal-dissolving or cyanid solution, then subjecting the mass ofmaterial to a rolling operation, thereby thoroughly stirring oragitating it and causing the oxygen of the atmospheric air to mingletherewith, the rolling operation at the same time forcing themetal-carrying solution through the strainers and into the channels,andfinally discharging said metal-carrying solution therefrom into the sumpand precipitating the precious metals from the solution, all as will bemore fully hereinafter set forth and claimed.

In the pending application for patent filed by me in the United StatesPatent Ofiice, Serial No. 80,768, I have shown, described, and claimedimproved means or apparatus for the extraction of the precious metalsfrom pulverized or finely-divided ores, said apparatus being welladapted to be employed in carrying out the improved method or process4oforming the subject of the present application for patent.

The object I have in view is to so treat the suitably-prepared ore thatit will be more thoroughly and quickly acted upon by the solution, theore at the same time being spread out in a comparatively thin layer andstirred or agitated, so as to expose it to the action of atmosphericair, the result beingthat a greater amount of oxygen is absorbed and theoperation is accomplished in much less time and with less power than isusually required in treating material of this character.

I am of course aware that vprocesses and means for agitating pulverizedores so as to combine oxygen therewith have been devised prior to myinvention. Therefore I do not claim such broadly.

In the accompanying drawings, Figure l is a plan View of agold-extracting plant or apparatus capable of being employed in carryingout my improved process. Fig. 2 is a longitudinal sectional view takenon line 2 2 of Fig. 1. Fig. 3 is a transverse sectional View, enlarged,taken on line 3 3 of Fig. 1, showing the channels and strainers orfilters. Fig. ais a sectional view,'enlarged, taken on line 4 4 of Fig.1; andFig. 5 is a partialside elevation, enlarged, showing portions ofthe mechanism for actuating the pulp-agitating roll.

In carrying out my improved process I may provide a series ofsubstantially level floors a a, made, say, ofcement. Each floor has aseries of longitudinallyextending narrow grooves or channels 0 0 formedtherein, the sides of which may be faced with strips of wood f. Thegrooves are slightly inclined, each terminating at its lower end in alarger or transverse groove d, termed a launder.

(See Fig. 4.) A suitable filter or strainer 8 covers each of thechannels, so arranged that the liquid solution may pass through thestrainers,while excluding the ore or material. In the drawings, Fig. 1,I have represented a series of four rectangular-shaped floors to. Theseare bounded by circumscribing walls I), having a height, say, of teninches, and are covered with cement or other suitable material, so as toprevent the absorption of the solution containing the dissolved preciousmetals. The said floor may be arranged so as to form two double floorseach having a transverse dividing or bridge wall b',as clearly shown.(See also Fig. 4.) Each of the lower floors (being the ones at the left)has a longitudinally extending launder d arranged just exterior of theinner side walls I) and communicating with the sump-tank E, containingthe strong solution. Parallel with the other or outer side wall isarranged another launder d the same extending to and across the lowerend of the floor, but exterior of it, and communicates with thesump-tank D, containing the weak solution. A valved connection, 71 isinterposed between the ends of the launders d and the adjacent ends ofthe corresponding cross-launders d. A similar connection h is locatedbetween the ends of the opposite launder d and the other ends of thesaid cross-lannders, as clearly shown in Fig. 1. The valved connectionspass through the adjacent walls I) and form water-tight jointstherewith. The bottom of each laun der d is inclined, so as to directthe flow of the saturated solution toward the center, at which point itis in open communication with the sump-tank E, containing strongsolution. The other launders d are each inclined throughout its lengthand in open communi cation with the corresponding sump-tank D,containing weak solution.

In a plant. embodying my improvement and adapted for the chemicalextraction of the precious metals from slime-pulp the ground plan mayhe, say, one hundred and twentyeight feet by sixty feet and having atone end thereof the elevated tanks AB C for water, strong solution, andweak solution, respectively, each tank being, say, fourteen feetdiameter by ten feet deep. At the opposite end of the plant and locatedbetween the two series of double floors a a are placed two sunkensump-tanks D E for the weak and strong solutions, respectively,.eachtank being twenty feet diameter by six feet deep. There are alsoemployed four slightly-elevated salt-leach tanks F, (one for each floora,) each tank being, say, twelve feet diameter by six feet deep andadapted to contain some fifteen tons of pulverized ore. The said tanks Fare charged with the pulverized ore and form reservoirs from which theore is shoveled or discharged onto the treating floors a.

I may stat e here that I prefer-to arrange the several floors, tanks,850., so as-to form a duplex or double plant or system substantially asrepresented in Fig. l of the drawings, the arrangement being such thatwhile the ore is being treated on the floors of one half of the plantthe other half of the plant may be cleaned up, thus working themechanism, &c., alternately. By means of my invention the charge of orespread evenly over one double floor may be thoroughly agitated andtreated duri'ngacontinuous run, say, of twelve hours, the other doublefloor meanwhile having the solution drawn therefrom into the respectivetanks, followed by removing the treated material or ore from the fiooronto the wastedump and recharging with fresh ore from the supply tanksF, substantially as before stated.

In the drawings I have represented the rolling or ore-agitatingmechanism R as consisting ofa suitable roll m, extending transversely ofthe floor a, and means for slowly propelling the roll to and fro alongthe floor. The roll is secured to a shaft n, the latter being above andextending beyond the side walls 6 and. adapted to revolve in suitablebearings are cured to the two endless side chains or driving connections19 p. Theselatter are mounted on suitable sprocket-wheels secured to thetwo end shafts 1' r, revolving in bearings located at the upper andlower ends, respectively, of each floor. An end of one shaftsay theupper one r-is extended and carries a worm-gear t, meshing into andactuated by a worm if of the short driving-shaft to. On the latter shaftare mounted two loose clutchpulleys w 10, adapted to be revolved inopposite directions by open and crossed driving-belts in a well-knownmanner.- A sliding clutch member is mounted on and revolves thepulley-shaft-that is, when the shipperarm y, connected with the clutch,is swung to the left the clutch engages the corresponding pulley to,thereby causing the shaft to revolve in one direction. By moving theship per to the right the clutch is withdrawn from pulley w and engagespulley 20, thus adapting the shaft to be revolved in the oppositedirection. It is obvious that the driving mechanism just described isadapted to propel the chainsp simultaneously and in unison in eitherdirection, thereby correspondingly actuating the roller m and agitatingthe pulp or material beneath it. The action of the roll serves not onlyto stir up or agitate the pulp, so that it becomes thoroughly aerated orexposed to the atmosphere, but it at the same time forces some of themetal-charged solvent or solution downwardly through the screens 8 andinto the channels or ducts c, communicating with the end launder d.

In order to automatically reverse the direction of the traveling chainspwhen the roll arrives at the end of the floor or at any otherpredetermined point, as desired, the chain contiguous to the clutchmechanism may be provided with two dogs 1) 1', arranged or disposed withrespect to the roll so that at or about the instant the latter arrivesat the end of the floor or run the corresponding dog will engage theshipper-arm y and swing it to the opposite extreme, thus clutching theshaft to to the other driving-pulley,and since the latter pulleyrevolves in a reverse direction to that of its fellow pulley it followsthat the chains movement will be correspondingly changed, thuspropelling the roll back again, the operation being continued as long asdesired. By placing the shipper in the central or vertical position theclutch will be inactive or disengaged from both pulleys, the roll thenbeing rendered inoperative.

The manner of extracting the precious metals from ores by means of myinvention is substantially as follows: The auriferous chloridized ore ina finely-divided state is first delivered into the leach-tanks orsaltleach tanks F. After the ore is thoroughly leached it-is dischargedtherefrom onto one of the empty double treating-floors a a and leveledoff, the quantity of material forming a charge being sufficient to makea layer, say, three inches deep. This is followed by cover- TIC ing thesurface of the said material with a strong solution drawn from tank 13until the liquid attains a mean depth of about one inch. The solutioncontained in said tank B carries the proper amount of cyanid of potassium or other suitable chemical dissolving agent for the preciousmetals. After the solvent-supply to the floor has been cut off the saidrolling mechanism R is set in motion,-

whereby the heavy rolls on are drawn back and forth alternately andlongitudinally of the floors, the action of the rolls being tothoroughly agitate the material thereunder, so that all the ore isbrought into intimate contact with the solution and with the atmosphericair, while at the same time some of the solution is forced through thescreens or strainers 5 into the groove 0 beneath. This rolling operationis continued uninterruptedly, say, for twelve hours, at the end of whichtime it will be found that practically all the precious metalspreviously contained in the ore in a free state have been dissolved outand combined with the solution then lying in the grooves c and laundersd. The two valved connections h are next opened, thus permitting thecharged or strong solution to flow freely from the said grooves andlaunders into the sump-tank E. From the latter the solution is pumpedinto the storage-tank B. The two valves h are next closed and weaksolution from tank 0 admitted to the material lying on the twotreating-floors, followed by rerolling the pulp a short time, the resultbeing to thoroughly wash out any solution remaining therein. Aftercompleting the rolling operation the valves h are opened, and thesolution thus washed from the pulp flows from the end launders (1 intothe outer launder d in open communication with the sump-tank D, and fromthe latter the weak solution is pumped into the elevated tank G. Theresidue or washed pulp is now removed from the treating-floors, thuspractically completing the operation, the entire time consumed being,say, twenty-four hours for one charge. During this time the other pairof treating-floors a a has been suitably charged with ore and solvent,the combination or pulp being kept continuously agitated by means of thecorresponding rolling device, all substantially as hereinbeforedescribed. After a sufficient quantity of the saturated or strongsolution has been collected in the tank 13 it is drawn off and treatedin the usual manner to separate the metals therefrom.

I claim as my invention and desire to secure by United States LettersPatent- 1. The process or method hereinbefore described of extractingprecious metals from finely-divided materials or ores, which consists inspreading a comparatively thin layer of the material over asubstantially'flat and large working surface provided with drainageducts or channels; then covering said material with suitablemetahdissolving or cyanid solution; then passing a heavy roll back andforth over the charge of material, &c., thereby at the same timethoroughly agitating o1.- stirring the charge and forcing some of thesolution into the drainage-ducts; then discharging said solution intothe sump, and finally precipitating the precious metal from thesolution.

2. The improvement in processes of extracting precious metals fromfinely-divided ores, which consists in spreading a comparatively thinlayer of the suitably-prepared ores treated with metal-dissolvingsolution over a substantially fiat and broad floor; then rolling aweight back and forth over the material lying upon said floor, therebyat the same time thoroughly agitating and aerating the material andforcing out some of the metal-carrying solution, and finally treatingthe latter to extract or precipitate the precious metal therefrom.

Signed at Providence, Rhode Island, this 8th day of February, 1902.

LEVI 13. DARLING.

Witnesses:

GEO. I-I. REMINGTON, HENRY P. STONE.

